﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HBase.util {
    public class CRC {
        #region CRC16
        public static byte[] CRC16(byte[] data) {
            int len = data.Length;
            if (len > 0) {
                ushort crc = 0xFFFF;

                for (int i = 0; i < len; i++) {
                    crc = (ushort)(crc ^ (data[i]));
                    for (int j = 0; j < 8; j++) {
                        crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);
                    }
                }
                byte hi = (byte)((crc & 0xFF00) >> 8); //高位置
                byte lo = (byte)(crc & 0x00FF); //低位置

                return new byte[] { hi, lo };
            }
            return new byte[] { 0, 0 };
        }


        public static ushort getCRC16(byte[] data) {
            ushort crc = 0xFFFF;
            int len = data.Length - 2;
            if (len <= 0) {
                return crc;
            }
            for (int i = 0; i < len; i++) {
                crc = (ushort)(crc ^ (data[i]));
                for (int j = 0; j < 8; j++) {
                    crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);
                }
            }
            

            return crc;

        }
        public static bool checkCRC16(byte[] data) {
            int len= data.Length-2;
            if (len <= 0) {
                return false;
            }

            ushort crc = getCRC16(data);
            byte hi = (byte)((crc & 0xFF00) >> 8); //高位置
            byte lo = (byte)(crc & 0x00FF); //低位置

            return hi== data[len]&& lo == data[len+1];
           
        }

        public static void setCRC16(byte[] data) {
            int len = data.Length - 2;
            if (len <= 0) {
                return  ;
            }

            ushort crc = getCRC16(data);
            byte hi = (byte)((crc & 0xFF00) >> 8); //高位置
            byte lo = (byte)(crc & 0x00FF); //低位置 
            data[len] = hi;
            data[len + 1]= lo;

        }
        #endregion

        #region ToCRC16
        public static string ToCRC16(string content) {
            return ToCRC16(content, Encoding.UTF8);
        }

        public static string ToCRC16(string content, bool isReverse) {
            return ToCRC16(content, Encoding.UTF8, isReverse);
        }

        public static string ToCRC16(string content, Encoding encoding) {
            return ByteToString(CRC16(encoding.GetBytes(content)), true);
        }

        public static string ToCRC16(string content, Encoding encoding, bool isReverse) {
            return ByteToString(CRC16(encoding.GetBytes(content)), isReverse);
        }

        public static string ToCRC16(byte[] data) {
            return ByteToString(CRC16(data), true);
        }

        public static string ToCRC16(byte[] data, bool isReverse) {
            return ByteToString(CRC16(data), isReverse);
        }
        #endregion

        #region ToModbusCRC16
        public static string ToModbusCRC16(string s) {
            return ToModbusCRC16(s, true);
        }

        public static string ToModbusCRC16(string s, bool isReverse) {
            return ByteToString(CRC16(StringToHexByte(s)), isReverse);
        }

        public static string ToModbusCRC16(byte[] data) {
            return ToModbusCRC16(data, true);
        }

        public static string ToModbusCRC16(byte[] data, bool isReverse) {
            return ByteToString(CRC16(data), isReverse);
        }
        #endregion

        #region ByteToString
        public static string ByteToString(byte[] arr, bool isReverse) {
            try {
                byte hi = arr[0], lo = arr[1];
                return Convert.ToString(isReverse ? hi + lo * 0x100 : hi * 0x100 + lo, 16).ToUpper().PadLeft(4, '0');
            } catch (Exception ex) { throw (ex); }
        }

        public static string ByteToString(byte[] arr) {
            try {
                return ByteToString(arr, true);
            } catch (Exception ex) { throw (ex); }
        }
        #endregion

        #region StringToHexString
        public static string StringToHexString(string str) {
            StringBuilder s = new StringBuilder();
            foreach (short c in str.ToCharArray()) {
                s.Append(c.ToString("X4"));
            }
            return s.ToString();
        }
        #endregion

        #region StringToHexByte
        private static string ConvertChinese(string str) {
            StringBuilder s = new StringBuilder();
            foreach (short c in str.ToCharArray()) {
                if (c <= 0 || c >= 127) {
                    s.Append(c.ToString("X4"));
                } else {
                    s.Append((char)c);
                }
            }
            return s.ToString();
        }

        private static string FilterChinese(string str) {
            StringBuilder s = new StringBuilder();
            foreach (short c in str.ToCharArray()) {
                if (c > 0 && c < 127) {
                    s.Append((char)c);
                }
            }
            return s.ToString();
        }

        /// <summary>
        /// 字符串转16进制字符数组
        /// </summary>
        /// <param name="hex"></param>
        /// <returns></returns>
        public static byte[] StringToHexByte(string str) {
            return StringToHexByte(str, false);
        }

        /// <summary>
        /// 字符串转16进制字符数组
        /// </summary>
        /// <param name="str"></param>
        /// <param name="isFilterChinese">是否过滤掉中文字符</param>
        /// <returns></returns>
        public static byte[] StringToHexByte(string str, bool isFilterChinese) {
            string hex = isFilterChinese ? FilterChinese(str) : ConvertChinese(str);

            //清除所有空格
            hex = hex.Replace(" ", "");
            //若字符个数为奇数，补一个0
            hex += hex.Length % 2 != 0 ? "0" : "";

            byte[] result = new byte[hex.Length / 2];
            for (int i = 0, c = result.Length; i < c; i++) {
                result[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
            }
            return result;
        }
        #endregion
    }
}
